Automatic injection device for administering a fixed dose

ABSTRACT

An injection device for administering a substance, including a housing, a plunger rod which can be moved relative to the housing, at least one retaining element associated with the rod to hold the rod relative to the housing, and a displaceable locking sleeve which can be displaced relative to the housing from one position in which the sleeve holds the at least one retaining element in a retaining position to a second position in which the at least one retaining element is released.

CROSS-REFERENCED RELATED APPLICATIONS

This application is a continuation of International Patent Application No. PCT/CH2009/000267 filed Jul. 31, 2009, which claims priority to German Patent Application No. DE 10 2008 037 310.9 filed Aug. 11, 2008, the entire contents of both of which are incorporated herein by reference.

BACKGROUND

This application relates to devices for injecting, delivering, infusing, administering or dispensing a substance, and to methods of making and using such devices. More particularly, it relates to a device for self-administering a fixed dose of a substance. Such a device may be thought of and referred to as an injection pen, a fixed-dose injection pen or a fixed dose pen, and provides a convenient, efficient way of self-administering a substance stored in an ampoule or syringe inside the injection pen on a one-off basis.

An example of an injection device for administering a fixedly set dose on a one-off basis, wherein the dose can be pre-set, is known from patent specification DE 10 2006 038 103 A1 owned and filed by the owner of the present application.

SUMMARY

An object of the present invention is to provide an injection device for administering a fixed, pre-set quantity of a substance on a one-off basis, wherein the device has a simple design and is easy to operate.

In one embodiment, the present invention comprises an injection device for administering a substance, comprising a housing, a plunger rod which can be moved relative to the housing, at least one retaining element associated with the rod to hold the rod relative to the housing, and a displaceable locking sleeve which can be displaced relative to the housing from one position in which the sleeve holds the at least one retaining element in a retaining position to a second position in which the at least one retaining element is released.

In one embodiment, the present invention comprises an injection device comprising a housing, a plunger rod which can be moved in the housing and on which at least one retaining element is provided that holds the plunger rod relative to the housing, and further comprising a displaceable locking unit, e.g. a cover sleeve, which can be displaced inside the housing, and which in a first position holds the at least one retaining element positively in a retaining position relative to the housing and in a second position releases the at least one retaining element.

In one embodiment, the present invention comprises an injection device having a housing, by which the injection device can be held by a user. A plunger rod is provided inside the housing, which is able to push against a stopper or piston of an ampoule or syringe, likewise disposed inside the injection device, to force out a substance contained inside the ampoule or syringe and administer it by pushing against the stopper, e.g. by a needle. In some embodiments, the plunger rod has at least one retaining element which can be moved or outwardly deflected, for example a resilient arm with a radially projecting locating region. The at least one retaining element holds the plunger rod in a fixed position relative to the housing, in some embodiments on or against the housing, so that it is not able to move. A moving or sliding locking element is also provided on or in the injection device, for example a sleeve, e.g. a protective sleeve, which is able to move relative to the housing and which holds the at least one retaining element in a fixed position relative to the housing when the locking element or sleeve is in a first position. The at least one retaining element can be released when the locking element or sleeve is moved out of the first position so that the coupling between the plunger rod and the injection device or housing is released, and the plunger rod can be moved or pushed inside the injection device to initiate or effect the injection.

In some preferred embodiments, the locking element or sleeve is a protective sleeve located or disposed at or in the distal region (this region may also be thought of and/or referred to as the front, forward or needle region) of the injection device and extending out from the injection device. The protective sleeve can be pushed relative to the injection device or relative to the housing of the injection device, e.g. in an axial direction into the housing of the injection device, if the injection device is placed on or against a surface such as a user's or patient's skin. In some embodiments, the protective sleeve is mounted in the housing of the injection device so that it is prevented from turning. When the housing of the injection device is pushed toward or against the skin, the protective sleeve is moved or pushed into the housing or into the injection device, in some preferred embodiments after overcoming a minimum opposing force caused by a releasable catch connection. In this case, the injection device and/or its housing moves toward the skin surface.

In some preferred embodiments, at least one rib or catch or retaining step is provided on the housing, against which the at least one retaining element can be retained. The rib or retaining step may have a surface to which a longitudinal or axial axis of the injection device extends perpendicularly. In some preferred embodiments, the rib or step may be chamfered so that the at least one retaining element of the plunger rod can be released more easily when it is no longer retained or secured by the displaceable protective sleeve. The at least one retaining element of the plunger rod also has a retaining region, which complements the abutment surface of the retaining step. It can be, thus, likewise slightly chamfered.

In some preferred embodiments, an injection spring element is provided, which is supported on or by the housing or an element fixedly connected or latched to the housing, e.g an end cap. The spring element pushes on the plunger rod in the distal direction (this direction may also be thought of and/or referred to as the forward, injection or delivery direction). In some embodiments, the injection spring element is tensed when the injection device is in the initial position and expends a force which is enough to move the at least one retaining element out of the retaining or locating position when the retaining element is no longer retained or locked by the lock or protective sleeve. As a result, and due to the force of the injection spring element pushing on the plunger rod, the rod is moved relative to the injection device or relative to the housing toward the stopper of the ampoule or syringe to initiate the dispensing process.

In some embodiments, the protective sleeve is locked so that it is not able to rotate in the housing of the injection device or inside the injection device. In some embodiments, it may be locked by an axially extending groove and/or a web of the protective sleeve which co-operates with a co-operating, complementary web and/or an axial groove of the injection device or housing. Such an arrangement may also be thought of and/or referred to as an axial guide.

In some preferred embodiments, a spring is provided which is supported against the injection device or its housing and which pushes on the displaceable protective sleeve so that the protective sleeve spring is able to apply pressure to the protective sleeve in the distal direction. When the injection device is placed on or against a surface and moved toward it, the protective sleeve can be pushed into the injection device against the force of the protective sleeve spring, causing a compression and hence tensing of the protective sleeve spring.

In some embodiments, an ampoule or syringe is provided in the injection device, which is fixedly connected to the housing or fixedly retained in the injection device, for example by one or more stops and/or by the plunger rod pushing against the ampoule or stopper of the ampoule. In some preferred embodiments, the syringe has an injection needle at the distal end, which may be made safe by being covered by a removable needle guard cap. The needle is disposed on or in the injection device so that it is surrounded by the protective sleeve when the latter is pushed out and exposed when the protective sleeve is pushed back, so that when the injection device is pushed onto or against a surface, e.g. the skin, the protective sleeve can be pushed in so that the injection needle, now exposed, can be used to effect the injection. In some embodiments, the injection is effected manually by pushing the injection device onto or against a surface, obviating the need to operate a button or trigger element for the injection process. In this respect, the protective sleeve is mounted in or on the injection device so that when the injection device is pushed onto or against a surface, against or on which the protective sleeve then lies, an initial force must be overcome to enable the protective sleeve to be pushed in. This helps ensures that the injection takes place quickly once the initial force has been overcome and the protective sleeve is pushed back quickly due to the subsequent force, thus enabling a rapid piercing action by the needle.

Another aspect of the present invention is that it relates, in some embodiments, to an injection device which can be assembled from few individual parts, for example only three or four individual parts, which may be molded from a plastic, e.g. a housing, protective sleeve, plunger rod and, optionally, an end cover or cap. In this respect, only a single spring is provided for the injection and, optionally, another spring for the protective sleeve.

In accordance with some preferred embodiments of the present invention, an injection device can be obtained by which it is possible to set a single dose, for being administering once, after which the injection device automatically locks after the administering. Accordingly, the administered or dispensed volume is fixed on a predefined basis, e.g. it may be the entire contents of the ampoule or syringe contained in the injection device. In some preferred embodiments, dispensing takes place automatically after piercing, an advantage of which is that no other operating mechanism needs to be operated to initiate the dispensing operation after piercing. The dispensing operation takes place totally automatically after the piercing operation. In some preferred embodiments, the injection device has a safety needle guard and locks or protects the injection needle after use. In other words, in some embodiments, after n injection has taken place, the protective sleeve is automatically returned or pushed back out in the axial direction beyond the injection needle.

Another aspect of the present invention is that it relates to a method of assembling or fitting an injection device comprising, in some embodiments, at least two or exactly two sub-units, wherein an ampoule or syringe to be inserted in the device is not regarded as a sub-unit. When assembling the injection device from the two sub-units, an injection spring is not tensed until the sub-units are assembled. In some preferred embodiments, the injection spring is an integral part of one of the sub-units and is in the relaxed, non-compressed or non-tensed state when the two sub-units are not assembled. This helps ensure that processes which might cause impairment or alteration due to the pressure expended by a tensed injection spring do not start to occur on assembly of the sub-units.

In some preferred embodiments, one of the two units comprises the housing of the injection device and, optionally, also a protective sleeve which is inserted in the housing, is able to slide relative to it and may extend out from the distal region of the housing. The second sub-unit comprises a plunger rod, an injection spring and an injection spring support element, and the injection spring is tensed between the injection spring support element and plunger rod and can be compressed, for example. The plunger rod or plunger rod element may be moved relative to the injection spring support element and can be pushed into it guided by the injection spring support element, so that the injection spring can be tensed or compressed between the plunger rod and injection spring support element. When the injection device is being assembled, a syringe or ampoule may be inserted between the first sub-unit and the second sub-unit prior to assembly, e.g., pushed into the first sub-unit. The second sub-unit can then be coupled to, inserted in or pushed into the first sub-unit. In this respect, the plunger rod or distal end of the plunger rod is pushed against the syringe or ampoule or against a stopper which is able to slide in the syringe or ampoule. Since no fluid or no substance is able to escape from the ampoule or syringe in the initial state because a needle guard element is fitted and the plunger rod is pushed relative to the injection spring support element due to the pressure of the stopper, as the second sub-unit is inserted in the first sub-unit, the injection spring is tensed. A protective sleeve spring may also optionally be provided between the first and the second sub-unit or on the second sub-unit, which lies between the injection spring support element on the one hand and the protective sleeve on the other hand in the assembled state, so that the protective sleeve causes the protective sleeve spring to tense or compress as it is inserted in the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating an embodiment of an injection device in accordance with the present invention in an initial state;

FIG. 2 is an exploded view of the injection device illustrated in FIG. 1 prior to assembly;

FIG. 3 shows the injection device illustrated in FIG. 2 in the partially assembled state; and

FIGS. 4A to 4C illustrate the sequence which takes placed during an injection using the injection device of FIG. 1.

DETAILED DESCRIPTION

With regard to fastening, mounting, attaching or connecting components of the present invention, unless specifically described as otherwise, conventional mechanical fasteners and methods may be used. Other appropriate fastening or attachment methods include adhesives, welding and soldering, the latter particularly with regard to the electrical system of the invention, if any. In embodiments with electrical features or components, suitable electrical components and circuitry, wires, wireless components, chips, boards, microprocessors, inputs, outputs, displays, control components, etc. may be used. Generally, unless otherwise indicated, the materials for making embodiments of the invention and/or components thereof may be selected from appropriate materials such as metal, metallic alloys, ceramics, plastics, etc. Unless otherwise indicated specifically or by context, positional terms (e.g., up, down, front, rear, distal, proximal, etc.) are descriptive not limiting. Same reference numbers are used to denote same parts or components.

FIG. 1 illustrates an injection device with a housing 1, which has ribs or webs 1 a on its internal face extending in the axial direction. Disposed at a proximal end of the each rib 1 a is a respective retaining element 3 a in the form of a resilient arm which locates or is urged or biased radially outward. The retaining elements 3 a are attached to a plunger rod 3 and retain it in the illustrated axial position. An injection spring 5 is provided in the rear or proximal region of the injection device, which is supported against an end cap 4 latched to or into the housing and which pushes on the plunger rod 3 and pushes the retaining elements 3 a of the plunger rod 3 in the distal (forward) direction. The retaining elements 3 a of the plunger rod 3 are retained in the locating or retained position on the edges of the webs 1 a by arms 2 a of a protective sleeve 2, in a positively fitting arrangement or with a slight clearance, so that an injection spring 5 cannot push the plunger rod 3 in the distal direction.

Disposed at the distal end of the plunger rod 3 is an ampoule or syringe 7 with a stopper 7 a which is able to slide in it, against which the plunger rod 3 is able to push. Disposed at the distal or front end of the syringe 7 is an injection needle 7 b, on which a needle guard cap 7 c is fitted, which is removed before using the injection device. The protective sleeve 2 has lugs 2 b projecting radially outward in the region of the front or distal half, which locate in a co-operating groove or recess 1 c of the housing to generate an initial resistance when the protective sleeve 2 is pushed by a user holding or urging the housing 1 against a surface. As the force applied by the user pushing on the housing 1 in the distal direction becomes stronger, these retaining elements 1 c are released from their retaining position and release the protective sleeve so that it can slide axially in the injection device 1 abruptly or in a saccadic movement into the injection device 1, as a result of which the injection device 1 is applied in a saccadic movement to the surface causing it to be pierced by the needle 7 b.

A protective sleeve spring 6 is provided in the rear or proximal part of the injection device, which is supported against the housing 1 of the injection device or, as in the depicted exemplary embodiment, against an end cap 4 fitted on or connected to the housing 1 and which pushes against the protective sleeve 2 in the distal direction.

FIG. 2 is an exploded view of the injection device illustrated in FIG. 1, in which the individual components of the injection device described above may be seen. The protective sleeve 2 has two arms 2 a pointing in the axial direction with proximal end or retaining regions 2 d and a releasing cut-out 2 c disposed between the arms 2 a axially offset from the retaining regions 2 d. The plunger rod 3 has two retaining elements 3 a and 3 a′, which can be moved apart from one another by the retaining regions 2 d for example and/or secured to prevent them from being pressed together.

FIG. 3 illustrates the partially assembled individual components with the protective sleeve 2 inserted in the housing 1 and the plunger rod 3, injection spring 5 and end cap 4 assembled to form a unit.

FIGS. 1, 4A, 4B and 4C illustrate an embodiments of an operational sequence which takes place during an injection using the injection device, starting from the state in which it is supplied, illustrated in FIG. 1.

The injection device is primed by the injection spring 5, which is compressed or tensed between the plunger rod 3 and end cap 4. The protective sleeve 2 is mounted or suspended so that it is not able to turn in the housing 1 and is pushed into the front, forward or distal position by the protective sleeve spring 6. The syringe 7 is mounted in the housing 1 against stops or retaining elements 1 b, and is additionally guided in the protective sleeve 2 by arms or ribs 2 a and secured by webs 4 a of the end cap 4. The resilient elements 3 a associated with the rod 3 project radially outward, and sit against ribs 1 a in the housing 1 and are prevented from being deflected radially inward out of the retaining position by the proximal end 2 d of the arms 2 a of the protective sleeve 2.

The end cap 4 snap fits or latches into the housing 1. This snap-fit or latched connection is suitable to absorb the forces of the injection spring 5 and protective sleeve spring 6.

FIG. 4A illustrates the injection device in a released state after the protective sleeve 7 c has been removed from the injection needle 7 b. During piercing, the protective sleeve 2 is moved rearwardly toward or into the rear position until the resilient elements 3 a of the plunger rod 3 are released and able to deflect or move outwardly via a cut-out 2 e in the protective sleeve 2. Due to the chamfer on the ribs 1 a in the housing 1 and on the resilient elements 3 a of the plunger rod 3, the resilient elements 3 a of the plunger rod 3 are deflected outwardly by the force of the injection spring 5 so that the dispensing operation is automatically triggered. The injection spring 5 applies the force which is needed to deflect the resilient elements 3 a outward and thus release the plunger rod 3, which is pushed onto the stopper 7 a of the syringe 7 by the injection spring 5 pushing it into the syringe 7 and thus automatically triggering the dispensing operation.

The protective sleeve spring 6 lies against the proximal ends 2 d of the sleeve 2 and is compressed or tensed by the sleeve 2 as it is inserted.

FIG. 4B illustrates the injection device after a dispensing operation. As the injection spring 5 relaxes, the plunger rod 3 is pushed forward in the distal direction. The plunger rod 3 pushes against the stopper 7 a of the syringe 7 and empties the syringe 7 completely until the stopper 7 a is at the end of the glass body of the syringe 7. The two resilient elements 3 a and the plunger rod 3 slide across or along the ribs 1 a of the housing 1. At the end of the dispensing operation, one of the two resilient elements 3 a snaps over the end of one or more ribs 1 a in the housing 1 and causes a noise at the end of the dispensing operation, the so-called “end click,” and locks the plunger rod 3 to prevent it from being pushed back.

The other resilient element 3 a′ on the plunger rod 3 is retained by an arm 2 a on the protective sleeve 2 acting as a locking web in the outwardly deflected state.

FIG. 4C illustrates the injection device in a locked state after it has been removed from the injection site.

When the injection is terminated, the injection device is removed from the injection site. As this happens, the protective sleeve 2 is pushed into the front-most or distal position by the protective sleeve spring 6. The locking web 2 a of the protective sleeve 2 is pushed by the outwardly deflected resilient element 3 a′ on the plunger rod 3 until the resilient element 3 a′ snaps over the end of the locking web 2 a generating a sound or so-called “click.” In this state, the injection device is locked. The protective sleeve 2 can no longer be pushed in because it is blocked by the plunger rod 3, which sits against the three ribs 1 a in the housing 1.

Embodiments of the present invention, including preferred embodiments, have been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms and steps disclosed. The embodiments were chosen and described to illustrate the principles of the invention and the practical application thereof, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled. 

1. An injection device for administering a substance, comprising a housing, a plunger rod which can be moved relative to the housing, at least one retaining element associated with the rod to hold the rod relative to the housing, and a sleeve which can be displaced relative to the housing from one position in which the sleeve holds the at least one retaining element in a retaining position to a second position in which the at least one retaining element is released.
 2. The injection device as claimed in claim 1, wherein the sleeve has a recess for receiving the at least one retaining element in the second position.
 3. An injection device for administering a substance, comprising a housing, a plunger rod displaceable in the housing, on which at least one retaining element is provided for retaining the plunger rod relative to the housing, and a displaceable lock comprising a protective sleeve, which is able to slide inside the housing and holds the at least one retaining element in a retained position relative to the housing in a first position and which releases the at least one retaining element in a second position.
 4. The injection device as claimed in claim 3, in which the at least one retaining element is resilient and outwardly biased in a radial direction and comprises least one retaining region.
 5. The injection device as claimed in claim 4, wherein the housing comprises at least one abutment edge against which the at least one retaining element can be supported to prevent it from sliding in a distal direction in a first position and to prevent it from sliding in a proximal direction in a second position offset in the distal direction.
 6. The injection device as claimed in claim 5, wherein the protective sleeve is mounted in the injection device or in the housing so that it is prevented from rotating.
 7. The injection device as claimed in claim 6, wherein the protective sleeve is axially offset from a retaining region which holds the at least one retaining element in position, and has a recess to release the at least one retaining element after the protective sleeve has moved.
 8. The injection device as claimed in claim 7, further comprising an injection spring which is supported against the housing or against an element connected to the housing and which pushes the plunger rod in the distal direction.
 9. The injection device as claimed in claim 8, further comprising a protective sleeve spring which is supported against the housing of the injection device or an element connected to it and which pushes the protective sleeve in the distal direction.
 10. The injection device as claimed in claim 9, further comprising an ampoule with a stopper which can be pushed into the ampoule, wherein the ampoule is either mounted in the housing in a sliding arrangement or is mounted in the protective sleeve in a sliding arrangement.
 11. An injection device comprising two sub-units, one of said sub-units comprising a housing of the injection device and a protective sleeve in the housing, the sleeve able to slide relative to the housing, and the other sub-unit comprising a plunger rod, an injection spring and an injection spring support element.
 12. The injection device according to claim 11, wherein the plunger rod may be moved into and guided by the injection spring support element, so that the injection spring can be tensed between the plunger rod and injection spring support element as the two sub-units are assembled.
 13. The injection device according to claim 12, wherein when the injection device is being assembled, an ampoule may be positioned between the sub-units and the sub-units are moved toward each other whereby the plunger rod is urged against the ampoule or against a stopper in the ampoule causing the injection spring to be tensed.
 14. A method of performing an injection with an injection device, comprising the steps of: placing a distal end of the injection device on an injection surface, pushing a distal element into the injection device, thereby releasing a lock associated with a plunger rod of the injection device.
 15. The method according to claim 14, wherein the rod is biased by a spring.
 16. A method of assembling an injection device from two sub-units, wherein an injection spring associated with one of the sub-units is tensed when the sub-units are assembled.
 17. The method as claimed claim 16, wherein one sub-unit comprises a housing and the other sub-unit comprises a plunger rod, the injection spring and an injection spring support element, wherein the injection spring is tensed between the plunger rod and the injection spring support element as the sub-units are assembled. 